1. Field of the Disclosure
The present invention pertains to pressure support systems, and, in particular, to such pressure support systems employing a controller, breathing tube, an interface device, and a method of inductively transmitting power or signals between the patient interface device and the controller.
2. Description of the Related Art
Referring to FIG. 1, a conventional pressure support system 50 includes a gas flow generator 52, such as a blower, and is typically used as a continuous positive airway pressure (CPAP) or bi-level pressure support device. System 50 receives breathing gas, generally indicated by arrow C, from any suitable source, e.g., a pressurized tank of oxygen or air, the ambient atmosphere, or a combination thereof. Gas flow generator 52 generates a flow of breathing gas, such as air, oxygen, or a mixture thereof, for delivery to an airway of patient 54 at relatively higher and lower pressures, i.e., generally equal to or above ambient atmospheric pressure. Gas flow generator 52 is capable of providing a flow of breathing gas ranging in pressure from about 3-30 cmH2O. The pressurized flow of breathing gas, generally indicated by arrow D from gas flow generator 52, is delivered via a delivery conduit 56 to a breathing mask or patient interface 58 of any known construction, which is typically worn by or otherwise attached to patient 54 to communicate the flow of breathing gas to the airway of patient 54. Delivery conduit 56 also known in the art as a patient circuit.
Pressure support system 50 is what is known as a single-limb system, meaning that the patient circuit includes only one delivery conduit 56 connecting patient 54 to pressure support system 50. As such, an exhaust vent 57 is provided in delivery conduit 56 for venting exhaled gasses from the system as indicated by arrow E. Exhaust vent 57 can be provided at other locations in addition to or instead of in delivery conduit 56, such as in patient interface device 58. Exhaust vent 57 can have a wide variety of configurations depending on the desired manner in which gas is to be vented from pressure support system 50.
Pressure support system 50 includes a pressure controller in the form of valve 60 provided in delivery conduit 56. Valve 60 controls the pressure of the flow of breathing gas from flow generator 52 delivered to patient 54. Flow generator 52 and valve 60 are collectively referred to a pressure generating system because they act in concert to control the pressure and/or flow of gas delivered to patient 54. However, other techniques for controlling the pressure of the gas delivered to patient 54, such as varying the blower speed of flow generator 52, either alone or in combination with a pressure control valve, can be employed. Thus, valve 60 is optional depending on the technique used to control the pressure of the flow of breathing gas delivered to patient 54. If valve 60 is eliminated, the pressure generating system corresponds to flow generator 52 alone, and the pressure of gas in the patient circuit is controlled, for example, by controlling the motor speed of flow generator 52.
Pressure support system 50 further includes flow sensor 62 that measures the flow of the breathing gas within delivery conduit 56. Flow sensor 62 is interposed in line with delivery conduit 56, most preferably downstream of valve 60. Flow sensor 62 generates a flow signal that is provided to controller 64 and is used by controller 64 to determine the flow of gas at patient 54. Of course, other techniques for measuring the respiratory flow of patient 54 can be employed, such as measuring the flow directly at patient 54 or at other locations along delivery conduit 56 and communicating the measured flow by direct electrical connection between a flow sensor (not shown) and controller 64, measuring patient flow based on the operation of flow generator 52, and measuring patient flow using a flow sensor (not shown) upstream of valve 60.
Pressure support system 50 also includes pressure sensor 68 operatively coupled to controller 64 that detects the pressure of the gas at patient 54. Pressure sensor 68 is in fluid communication with patient interface 58 via delivery conduit 56. The pressure at patient 54 is estimated based on the known pressure drop that occurs in delivery conduit 56. Alternatively, the patient pressure can be measured directly at patient interface 58 using a pressure sensor (not shown) incorporated therein and communicating the measured pressure by direct electrical connection (not shown) between such pressure sensor (not shown) and controller 64.
Controller 64 may be, for example, a microprocessor, a microcontroller or some other suitable processor or processing device, that includes or is operatively coupled to a memory (not shown) that provides a storage medium for data and software executable by controller 64 for controlling the operation of pressure support system 50.
Input/output device 66 is provided for setting various parameters used by pressure support system 50, as well as for displaying and outputting information and data to a user, such as a clinician or caregiver.
Pressure support system 50 essentially functions as a CPAP pressure support system, and, therefore, includes all of the capabilities necessary in such systems in order to provide appropriate CPAP pressure levels to patient 54. This includes receiving the necessary parameters, via input commands, signals, instructions or other information, for providing appropriate CPAP pressure, such as maximum and minimum CPAP pressure settings. Other pressure support methodologies, include but are not limited to, BiPAP AutoSV, AVAPS, Auto CPAP, and BiPAP Auto.
It is known to provide a sensor at patient interface 58. See, e.g., U.S. patent application Ser. No. 10/777,572 to Burton (publication No. 2004/0163648). However, there is a challenge in transmitting information collected by such a sensor to controller 64 without providing cumbersome hardwired connections between these two elements. Wireless connections also present a problem in that it is desirable to minimize the mass or bulk contained on patient interface 58, which it typically worn by the user for extended periods of time. As a result, providing batteries, transmitters, and other items typically used in a wireless communication system at or on patient interface 58 is not appealing.